1. Field of the Invention
The present invention essentially relates to a process and apparatus for manufacturing solid particles from an ionically cross-linkable material in the presence of an ionic cross-linking agent, with high yields.
2. Description of the Related Art
Various processes of manufacturing solid particles, advantageously in substantially spherical form, thus constituting balls, from a solidifiable material originally in a form capable of flowing, are known. According to the prior art, the generation of drops of this material and the solidification thereof by contacting a solidifying agent, is usually provided. This technique is in particular used for the immobilization of a micro-organism by inclusion in the material. The immobilized micro-organisms may serve to produce fermented drinks such as wine and beer (FR-A-2 320 349 and FR-A-2 359 202). Their use has also been proposed for conventional champagnization (FR-A-2 432 045) as well as for making sparkling drinks with variable degrees of alcohol (FR-A-2 601 687). These publications, as well as others (in particular JP-A-57-150 385 or EP-A-173 915) have emphasized the performance of reactors with immobilized cells. FR-A-2 600 673 or FR-A-2 586 256 or EP-A-388 588 may also be cited as other documents.
These techniques have rendered possible the production of fermentations with mixtures of micro-organisms of different categories (mixtures of lactic bacteria and mixtures of yeasts).
However, the implementation of the process at an industrial level has encountered the difficulty of having sufficient quantities of particles produced at a high rate at low cost, and presenting a substantially spherical shape with a relatively homogeneous diameter.
In fact, according to the majority of known techniques, the solidifiable material is dropped in the form of drops in a liquid solidifying agent, generally contained in a tank, in a substantially vertical direction. The drawback of this system is that with the drops all dropping at the same spot on the surface of the solidifying liquid, the balls formed tend to agglomerate together in an indissociable mass. It has been sought to avoid this phenomenon by producing a vortex in the tank for receiving the drops containing the liquid solidifying agent, by circular stirring. However, the success of this operation is only partial since, as soon as the dropping rate of the drops on the one hand and the concentration of the balls already formed in the solidifying liquid on the other hand, are too high, the phenomenon of agglomeration of the balls cannot be totally avoided. In this way, the rate of producing the balls is generally limited, all the more so as these techniques impose a discontinuous production. This therefore constitutes a serious drawback for production on an industrial scale.
Furthermore, by these known techniques there appears another important drawback concerning the regularity of the shape of the balls. Upon the impact of a drop of the solidifiable material on the surface of the liquid solidifying agent, a certain crushing of this drop may be produced. This phenomenon is all the more detrimental in the case of the preparation of multi-layer balls, such as those described in document EP-A-173 915 in Example 5, page 14, as an irregularity in the thickness of the layers may be produced.
The present invention thus has for an object to solve the new technical problem consisting in providing a solution for manufacturing solid particles from an ionically cross-linkable material by contacting with an ionic cross-linking agent, at high rate, at a low cost, with the obtaining of particles of regular, substantially spherical shape, of relatively homogeneous mean diameter.
A further object of the present invention is to solve the new technical problem set forth above in particularly simple manner, making it possible to include micro-organism cells at high rate, without being detrimental to the activity of said cells, which constitutes an essential condition for the use of these particles containing included micro-organisms within the framework of fermentation processes, and particularly within the framework of the preparation of fermented or refermented drinks.
The present invention also has for its object to solve the new technical problems set forth above, with a solution which enables the ionic cross-linking time of the material to be adjusted extremely precisely and allowing a great versatility in the manufacture of particles having a diameter varying within broad limits.
Yet another object of the present invention is to solve the new technical problems set forth above, with a solution which allows recovery of the ionic cross-linking agent and recycling thereof.
These technical problems are solved simultaneously for the first time by the present invention in extremely simple, inexpensive manner, usable on an industrial scale.